Following the sudden, senseless murder of Jersey City police officer Melvin Santiago this past weekend, many cops across the Garden State are on high alert.

(Anton Prado Photography, ThinkStock)

"When police officers are setting out on their shift, they always know in the back of their minds they may encounter some horrible danger, but that's part of the job," said Nick Irons, professor of criminal justice at County College of Morris and former Sparta police sergeant. Irons said police are taught to maintain a heightened level of awareness because "anybody can become the person who's going to take your life -- man, woman, youngster, oldster -- it doesn't make any difference because you don't know what's going through their head at that time."

The result for officers can be unhealthy stress levels.

"It's always there. We're taught to be aware of our surroundings, to watch everything," Irons said. "We consider everybody a potential enemy, and that sometimes can become a problem because 99 percent of people are decent, kind, nice folks, but then we have to look at them as a potential killer of us or somebody else, and that's what makes life difficult. We're always aware, always on our toes in case something does happen. A police officer's stress is a major issue today."

He added that being a cop is a tremendous job.

"It's like having a front-row seat to the greatest show on earth, and yet one has to be aware when you're sitting in the front row that sometimes things can fly out and hit you," Irons said.